This Non-provisional application claims priority under 35 U.S.C. § 119(a) on patent application Ser. No(s). 2003-332469 filed in Japan on Sep. 24, 2003, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an image recording apparatus, and more particularly, to a technique for restoring recording defects by the image-recording elements of an inkjet recording apparatus or another image recording apparatus for recording images on a recording medium with a recording head having a plurality of image-recording elements.
2. Description of the Related Art
An inkjet image recording apparatus has an inkjet head (print head) in which a plurality of nozzles are arrayed, and the apparatus forms an image on a recording medium by moving the print head and recording medium in relation to each other, while ink is discharged from the nozzles.
In such an inkjet printer, due to clog of nozzles in the print head or a soiled meniscus surface on the ink in the head or other factors, ink may not be discharged or may not be discharged to a proper flight direction, hence missing spots may occur during printing for this reason. Such missing print is inconspicuous due to the considerable overlap in the shuttle-scan method, but nonuniformity by print defects occurs frequently in the case of a line head.
In view of the above, various methods have been proposed to retouch such missing print. Examples of known methods performed using an image recording apparatus for recording images with the dot matrix method (Japanese Patent Application Publication No. 9-24627, for example) include those in which the direction of the recorded medium is reversed while the medium is moved by a prescribed amount with respect to the recording head in the width direction, and the printing defect is retouched so that dot data to be printed is printed using a normally functioning dot print element at a prescribed distance from the defective dot print element in discharging the recorded medium if a printing defect is found. In this case, the prescribed amount is, for example, an integer multiple of the dot spacing, and the recording paper is directly discharged without retouching print defects if there are no print defects.
There are also inventions (Japanese Patent Application Publication No. 11-334047, for example) based on the use of a device for detecting nozzle defects in a linear inkjet, wherein images are formed using an auxiliary head jointly provided to the line head when there are defects in the line head nozzles.
There are further inventions (Japanese Patent Application Publication No. 2003-145734, for example) based on the use of a barcode recording apparatus for discharging ink from a plurality of nozzles disposed in the recording head to record a barcode, wherein a device is provided for detecting defective nozzles in the recording head, and if a defective nozzle is detected, the barcode is recorded so that the recording position of the barcode is shifted, rotated by 90°, or shifted and rotated by 90°.
Nevertheless, as cited in Japanese Patent Application Publication No. 9-24627, the direction of the once printed recorded paper is reversed, print defects are detected, and a determination is made as to whether to reprint, so regardless of the presence of a print defect, and the recording paper always reciprocates through the print head, therethrough productivity is low. Furthermore, only a normally functioning dot print element disposed at a prescribed distance from the defective dot print elements is used for printing, bringing about a drawback whereby the print defects are not necessarily completely retouched due to the skewing or other effect of the recording paper.
In the invention cited in Japanese Patent Application Publication No. 11-334047, there are drawbacks in that the apparatus configuration has considerable redundancy, because a compensating auxiliary head must be jointly provided for each color in addition to a regular line head. In the invention cited in Japanese Patent Application Publication No. 2003-145734, when a defective nozzle is detected, an attempt is made to shift the recording position of the barcode, or rotate the barcode by 90° to avoid streaking or other print defects in advance in the next barcode, and there is no provision for reprinting or taking other remedial action to retouch the recording medium with a print defect, therethrough there is a drawback in that the recording medium printed defectively is wasted